Collision mitigation for directional response in millimeter wave wireless local area network system

ABSTRACT

A method, apparatus, and system for beamforming training using a wireless transmit receive unit (WTRU). A WTRU may receive an indication of a number of space time slots (STSs) from an access point (AP) within a beacon frame during a beamforming training allocation. The WTRU may send a response signal to the AP in a specific STS based on a function of the number of STSs. The WTRU may receive an acknowledgement (ACK) from the AP confirming the response was received. Alternatively, the AP may send a signal indicating that a collision occurred and alter the number of STSs, and the WTRU may try again in the next beamforming training allocation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 16/492,233, filed on Sep. 9, 2019, which is theU.S. National Stage, under 35 U.S.C. § 371, of International ApplicationNo. PCT/US2018/021932 filed Mar. 12, 2018, which claims the benefit ofU.S. Provisional Patent Application No. 62/469,754, filed on Mar. 10,2017, the contents of which is hereby incorporated by reference herein.

BACKGROUND

In next generation mobile communications, there may be applications suchas enhanced mobile broadband (eMBB), massive Machine Type Communications(mMTC) and/or Ultra-Reliable Low Latency Communications (URLLC). Theseapplications may use a wide range of spectrum bands ranging from 700 MHzto 80 GHz. There may be a need to address issues that may arise in thewireless protocols for these new applications.

SUMMARY

A method, apparatus, and system for beamforming training using awireless transmit receive unit (WTRU). A WTRU may receive an indicationof a number of space time slots (STSs) from an access point (AP) withina beacon frame during a beamforming training allocation. The WTRU maysend a response signal to the AP in a specific STS based on a functionof the number of STSs. The WTRU may receive an acknowledgement (ACK)from the AP confirming the response was received. Alternatively, the APmay send a signal indicating that a collision occurred and alter thenumber of STSs, and the WTRU may try again in the next beamformingtraining allocation.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the drawings may be had from thefollowing description but is not intended to limit the scope of theembodiments but to merely serve as examples in conjunction with theaccompanying drawings, wherein like reference numerals in the figuresindicate like elements, and wherein:

FIG. 1A is a system diagram of an example wireless transmit/receive unit(WTRU);

FIG. 1B is a system diagram of an example radio access network and/or anexample core network;

FIG. 1C is a system diagram of an example communications system;

FIG. 2 is an example of IEEE 802.11ad beacon interval;

FIG. 3 is an example of sector level sweep (SLS) training;

FIG. 4 is an example format for a sector sweep (SSW) frame;

FIG. 5 is an example format for an SSW field in an SSW frame;

FIG. 6A is an example of an SSW feedback field in an SSW frame;

FIG. 6B is an example of an SSW feedback field in an SSW frame;

FIG. 7 is an example physical layer convergence procedure (PLCP)Protocol Data Unit (PPDU) carrying a beam refinement protocol (BRP)frame and training (TRN) fields;

FIG. 8 is an example of enhanced SLS implementation;

FIG. 9 illustrates an example of a baseline responding implementation;

FIG. 10 illustrates an example of configuration of the (space-time-slot)STS length in the directional multi-gigabit (DMG) beacon frame;

FIG. 11 illustrates an example of signaling the number of STS per beam;

FIG. 12 illustrates an example of varying the number of STS in a beam inaccess point (AP) directional Rx interval;

FIG. 13 illustrates an example of beacon with variable size; informationfor x beams may be signaled;

FIG. 14 illustrates an example of fixed beacon size; information forsome or all N beam may be signaled;

FIG. 15 illustrates an example of beacon with a fixed beacon sizeindicating the number of slots to wait before access;

FIG. 16 illustrates an example of collision identification within accesspoint (AP) directional receive interval;

FIG. 17 illustrates an example of collision interval for collisionidentification;

FIG. 18 . illustrates an example of station (STA) specific identifierfor STA specific collision identification;

FIG. 19 illustrates an example of sector ACK frame with equal collisionrecovery STS;

FIG. 20 illustrates an example of sector ACK frame with collision beamspecific recovery STS;

FIG. 21 illustrates an example of sector ACK frame with collisionidentification and STA specific beam collision/recovery signaling; and

FIG. 22 illustrates an example of enhanced SLS implementation.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example device 102, such as a wirelesstransmit receive unit (WTRUA). As discussed herein, a WTRU may beinterchangeable with an access point (AP), a station (STA), a userequipment (UE), a mobile device, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a tablet, an Internet of Things device,a personal computer, a wireless sensor, consumer electronics, a basestation, and the like.

The device 102, may be used in one or more of the communications systemsdescribed herein. As shown in FIG. 1A, the device 102 may include aprocessor 118, a transceiver 120, a transmit/receive element 122, aspeaker/microphone 124, a keypad 126, a display/touchpad 128,non-removable memory 130, removable memory 132, a power source 134, aglobal positioning system (GPS) chipset 136, and other peripherals 138.It should be appreciated that the device 102 may include anysub-combination of the foregoing elements while remaining consistentwith an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the device 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Adepicts the processor 118 and the transceiver 120 as separatecomponents, it should be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

Additionally, the processor 118 may comprise one or more processors. Forexample, the processor 118 may comprise one or more of: a generalpurpose processor, a special purpose processor (e.g., a basebandprocessor, a MAC processor, etc.), a digital signal processor (DSP),Application Specific Integrated Circuits (ASICs), Field ProgrammableGate Array (FPGAs) circuits, any other type of integrated circuit (IC),a state machine, and the like. The one or more processor(s) 118 may beintegrated or not integrated with each other. The processor 118 (e.g.,the one or more processors or a subset thereof) may be integrated withone or more other elements/functions (e.g., other functions such asmemory). The processor 118 may perform signal coding, data processing,power control, input/output processing, modulation, demodulation, and/orany other functionality that may enable the device to operate in awireless environment, such as a WLAN. The processor 118 may beconfigured to execute processor executable code (e.g., instructions)including, for example, software and/or firmware instructions. Forexample, the processor 118 may be configured to execute computerreadable instructions included on one or more of the processors (e.g., achipset that includes memory and a processor) or memory. Execution ofthe instructions may cause the device to perform one or more of thefunctions described herein.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station over an air interface 115.For example, in one embodiment, the transmit/receive element 122 may bean antenna configured to transmit and/or receive RF signals. In anotherembodiment, the transmit/receive element 122 may be an emitter/detectorconfigured to transmit and/or receive IR, UV, or visible light signals,for example. In yet another embodiment, the transmit/receive element 122may be configured to transmit and receive both RF and light signals. Itshould be appreciated that the transmit/receive element 122 may beconfigured to transmit and/or receive any combination of wirelesssignals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1A as a single element, the device 102 may include any number oftransmit/receive elements 122. The transmit/receive element 122 mayinclude one or more antennas. More specifically, the device 102 mayemploy multiple input multiple output (MIMO) techniques. Thus, in oneembodiment, the device 102 may include two or more transmit/receiveelements 122 (e.g., multiple antennas) for transmitting and receivingwireless signals over the air interface 116. The one or more antennasmay receive a radio signal. The processor may receive the radio signal,e.g., via the one or more antennas. The one or more antennas maytransmit a radio signal (e.g., based on a signal sent from theprocessor).

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the device 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling thedevice 102 to communicate via multiple Radio Access Technologies (RATs),such as UTRA and IEEE 802.11, for example.

The processor 118 of the device 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also facilitated output to the user via speaker/microphone 124,the keypad 126, and/or the display/touchpad 128. In addition, theprocessor 118 may access information from, and store data in, any typeof suitable memory, such as the non-removable memory 130 and/or theremovable memory 132. The non-removable memory 130 may includerandom-access memory (RAM), read-only memory (ROM), a hard disk, or anyother type of memory storage device. The removable memory 132 mayinclude a subscriber identity module (SIM) card, a memory stick, asecure digital (SD) memory card, and the like. In other embodiments, theprocessor 118 may access information from, and store data in, memorythat is not physically located on the WTRU 102, such as on a server or ahome computer (not shown).

Further, the device 102 memory (130 and/or 132) that may include one ormore elements/components/units for storing programming and/or data, suchas processor executable code or instructions (e.g., software, firmware,etc.), electronic data, databases, or other digital information. Thememory (130 and/or 132) may include one or more memory units. One ormore memory (130 and/or 132) units may be integrated with one or moreother functions (e.g., other functions included in the device, such asthe processor). The memory (130 and/or 132) may include a read-onlymemory (ROM) (e.g., erasable programmable read only memory (EPROM),electrically erasable programmable read only memory (EEPROM), etc.),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, and/or other non-transitorycomputer-readable media for storing information. The memory (130 and/or132) may be coupled to the processor 118. The processor 118 maycommunicate with one or more entities of memory (130 and/or 132), suchas via a system bus, directly, or the like.

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the device 102. For example, the power source 134may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the device102 may receive location information over the air interface 115 from abase station and/or determine its location based on the timing of thesignals being received from two or more nearby base stations. It shouldbe appreciated that the device 102 may acquire location information byway of any suitable location-determination method while remainingconsistent with an embodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1B is a diagram showing an example communications system 100 thatmay include at least one wireless transmit/receive unit (WTRU), such asa plurality of WTRUs, for instance WTRUs 102 a, 102 b, 102 c, and 102 d,one or more base stations 114 a and 114 b, a radio access network (RAN)105, a core network 109, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it should beappreciated that the disclosed embodiments contemplate any number ofWTRUs, base stations, networks, and/or network elements. Each of theWTRUs 102 a, 102 b, 102 c, 102 d may be any type of device configured tooperate and/or communicate in a wireless environment. By way of example,the WTRUs 102 a, 102 b, 102 c, 102 d may be configured to transmitand/or receive wireless signals and may include user equipment (UE), amobile station (e.g., a WLAN STA), a fixed or mobile subscriber unit, apager, a cellular telephone, a tablet, a personal digital assistant(PDA), a smartphone, a laptop, a netbook, a tablet, a personal computer,a wireless sensor, consumer electronics, an internet of things (loT)device, and the like.

Each of the base stations 114 a, 114 b may be any type of deviceconfigured to wirelessly interface with at least one of the WTRUs 102 a,102 b, 102 c, 102 d to facilitate access to one or more communicationnetworks, such as the core network 109, the Internet 110, and/or thenetworks 112. By way of example, the base stations 114 a, 114 b may be abase transceiver station (BTS), a Node-B, an eNode B, a Home Node B, aHome eNode B, a site controller, an access point (AP), a Personal BasicService Set (PBSS) Control Point (PCP), a wireless router, and the like.While the base stations 114 a, 114 b are each depicted as a singleelement in FIG. 1B, the base stations 114 a, 114 b may include anynumber of interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 105, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 115, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 115 may be established using any suitable radio accesstechnology (RAT).

The communications system 100 may be a multiple access system and mayemploy one or more channel access schemes, such as CDMA, TDMA, FDMA,OFDMA, SC-FDMA, and the like. For example, the base station 114 a in theRAN 105 and the WTRUs 102 a, 102 b, 102 c may implement a radiotechnology such as Universal Mobile Telecommunications System (UMTS)Terrestrial Radio Access (UTRA), which may establish the air interface115 using wideband CDMA (WCDMA). WCDMA may include communicationprotocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA(HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA)and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface115 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1B may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1B,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 109.

The RAN 105 may be in communication with the core network 109, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 109may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1B, it should be appreciatedthat the RAN 105 and/or the core network 109 may be in direct orindirect communication with other RANs (not shown) that employ the sameRAT as the RAN 105 or a different RAT. For example, in addition to beingconnected to the RAN 105, which may be utilizing an E-UTRA radiotechnology, the core network 109 may also be in communication withanother RAN (not shown) employing a GSM radio technology.

The core network 109 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network (not shown) connected to one ormore RANs (not shown), which may employ the same RAT as the RAN 105 or adifferent RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1B may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an 802.11 radio technology.

In one embodiment, the communications system 100 may have a wirelessnetwork with bearers that extend beyond the wireless network (e.g.,beyond a “walled garden” associated with the wireless network) and thatmay be assigned QoS characteristics.

Additionally, the communications system 100 may be a multiple accesssystem that provides content, such as voice, data, video, messaging,broadcast, and the like, to multiple wireless users. The communicationssystem 100 may enable multiple wireless users to access such contentthrough the sharing of system resources, including wireless bandwidth.For example, the communications systems 100 may employ one or morechannel access methods, such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and thelike.

FIG. 1C shows a diagram of an example wireless local area network (WLAN)122. One or more of the devices of WLAN 122 may be used to implement oneor more of the embodiments/features described herein. The WLAN 122 mayinclude, but is not limited to, Access Point (AP/PCP) 114 c, station(STA) 102 e, and STA 102 f. STA 102 e and 102 f may be associated withAP 114 c. The WLAN 122 may be configured to implement one or moreprotocols of the IEEE 802.11 communication standard, which may include achannel access scheme, such as DSSS, OFDM, OFDMA, or the like. A WLAN122 may operate in a mode, such as an infrastructure mode, an ad-hocmode, or the like. A STA may be a wired or wireless device, the same orsimilar to a wireless transmit receive unit (WTRU) as described herein.In one example, a STA 102 e, 102 f is a wireless mobile device. AnAP/PCP 114 c may be a wired or wireless device, the same or similar to aWTRU as described herein. In one example, an AP 114 c is a stationarydevice with both a wired and wireless interface.

A WLAN 122 operating in an infrastructure mode may comprise of one ormore APs 114 c communicating with one or more associated STAs 102 e and102 f. An AP 114 c and STA(s) 102 e and 102 f associated with the AP 114c may comprise a basic service set (BSS). For example, AP 114 c, STA 102e, and STA 102 f may comprise BSS WLAN 122. An extended service set(ESS) may comprise one or more APs, with one or more BSSs, and one ormore STAs associated with the APs (not shown). An AP 114 c may haveaccess to, and/or interface with, a distribution system (DS) 116, whichmay be wired and/or wireless and may carry traffic to and/or from the AP114 c. Traffic to a STA 102 e or 102 f in the WLAN 122 originating fromoutside the WLAN 122 may be received at an AP 114 c in the WLAN 122,which may send the traffic to one of the STA 102 e in the WLAN 122.Traffic originating from a STA 102 e in the WLAN 122 to a destinationoutside the WLAN 122 (e.g., to server 118) may be sent to an AP 114 c inthe WLAN 122, which may send the traffic to the destination (e.g., viaDS 116) to network 117 to be sent to server 118. Traffic between STAs102 e and 102 f within the WLAN 122 may be sent through one or more APs114 c. For example, a source STA 102 e may have traffic intended for adestination STA 102 f. STA 102 e may send the traffic to AP 114 c, and,AP 114 c may send the traffic to STA 102 f.

Alternatively, traffic between STAs 102 e and 102 f within a BSS WLAN122 may be peer-to-peer traffic. Peer-to-peer traffic may be sentbetween the source and destination STAs with a direct link setup (DLS)using an 802.11e DLS or an 802.11z tunneled DLS (TDLS) and may be sentdirectly. A WLAN 122 may use an Independent BSS (IBSS) mode and may haveno AP/PCP, and/or STAs, and may communicate directly with another WLAN(not shown). This mode of communication may be referred to as an“ad-hoc” mode of communication. In an ad-hoc mode WLAN 122, the STAs 102e and 102 f may communicate directly with each other without thecommunication being routed through an AP 114 c.

Devices may operate using IEEE 802.11 protocols, such as the AP/PCP 103may use the 802.11ac infrastructure mode of operation. The AP/PCP 114 cmay transmit a beacon and may do so on a fixed channel. The fixedchannel may be the primary channel. The channel may be 20 MHz wide andmay be the operating channel of the BSS. The channel may be used by theSTAs 102 e and 102 f and may be used to establish a connection with theAP/PCP 114 c.

STA(s) and/or AP(s) may use a Carrier Sense Multiple Access withCollision Avoidance (CSMA/CA) channel access mechanism. In CSMA/CA a STAand/or an AP may sense the primary channel. In one example, if a STA hasdata to send, the STA may sense the primary channel and if the primarychannel is detected to be busy, the STA may back off. In anotherexample, a WLAN or portion thereof may be configured so that one STA maytransmit at a given time (e.g., in a given BSS). Channel access mayinclude Request to Send (RTS) and/or Clear to Send (CTS) signaling. Inanother example, an exchange of a RTS frame may be transmitted by asending device and a response may be a CTS frame sent by a receivingdevice. In another example, if an AP has data to send to a STA, the APmay send an RTS frame to the STA. If the STA is ready to receive data,the STA may respond with a CTS frame. The CTS frame may include a timevalue that may alert other STAs to hold off from accessing themedium/channel while the AP initiating the RTS may transmit its data.Once the CTS frame is received from the STA, the AP may send the data tothe STA.

A device may reserve spectrum via a network allocation vector (NAV)field. For example, in an IEEE 802.11 frame, the NAV field may be usedto reserve a channel for a time period. A STA that wants to transmitdata may set the NAV to the time for which it may expect to use thechannel. When a STA sets the NAV, the NAV may be set for an associatedWLAN or subset thereof (e.g., a BSS). Other STAs may count down the NAVto zero. When the counter reaches a value of zero, the NAV functionalitymay indicate to the other STA that the channel is now available.

802.11ad may contain amendments that specify the MAC and PHY layers forvery high throughput (VHT) in the 60 GHz band. 802.11ad may support datarates up to 7 Gbits/s. 802.11ad may support three different modulationmodes (e.g., control PHY with single carrier and spread spectrum, singlecarrier PHY, and OFDM PHY). 802.11ad may use a 60 GHz unlicensed bandand/or a band that is available globally. At 60 GHz, the wavelength is 5mm, and compact antennas or antenna arrays may be used. An antenna maycreate narrow RF beams (e.g., at both transmitter and receiver). Thenarrow RF beams may effectively increase the coverage range and mayreduce the interference.

FIG. 2 is a diagram of an example Beacon Interval (BI) for an 802.11standard, such as 802.11ad. On the horizontal axis time 201 is shown. ABI 200 may last a period of time and may include one or more (e.g.,three) intervals including Beacon Transmission Interval (BTI) 202,Association Beamforming Training (A-BFT) 203, Announcement TransmissionInterval (ATI) 204, and/or Data Transmission Interval (DTI) 205. The BTI202, A-BFT 203, and/or ATI 204 may be included in a beacon headerinterval (BHI) 206.

The BTI 202 may include multiple beacon frames. A beacon frame may betransmitted by the PCP/AP on a different sector to cover some or allpossible directions. The frame may be used for network announcementand/or beamforming training of the PCP/AP's antenna sectors. A-BFT 203may be used by STAs to train the STAs' antenna sectors for communicationwith a PCP/AP. In the ATI 204, the PCP/AP may exchange managementinformation with associated and/or beam-trained STAs. The DTI 205 mayinclude one or more contention-based access periods (CBAPs) and/orscheduled service periods (SPs) where stations exchange data frames. InCBAP, multiple STAs may contend for a channel according to an 802.11enhanced distributed coordination function (EDCF). In an SP, a dedicatedpair of nodes may be assigned for communication between during acontention free period.

FIG. 3 is a diagram of an example beamforming training, such as a SectorLevel Sweep (SLS). The frame structure of 802.11ad may facilitate amehanism for beamforming training (e.g., discovery and tracking). Thebeamforming training protocol may comprise two components: SLS 304 and aBeam Refinement Protocol (BRP) 305. The SLS 304 may be used fortransmitting beamforming training. The BRP 305 may enable receivingbeamforming training and/or may refine (e.g., iteratively) the transmitand/or receive beams. For any beamforming training there may be aninitiator 302 and a responder 305. Transmission back and forth betweenthe initiator 302 and the responder 303 is shown in the vertical axis,and time 301 is shown in the horizontal axis. In one example of SLS 304,the initiator 302 may send an Initiator Sector Sweep (ISS) 306 a to theresponder 303 in one or more Sector Sweep (SSW) Frames 307 a. After, theresponder 303 may send a Responder Sector Sweep (RSS) 306 b in one ormore SSW Frames 307 b. Once the initiator 302 receives SSW Frames 307 bfrom the RSS 306 b, it may then send SSW Feedback 308 a. The responder303 may send an SSW Acknowledgement (ACK) 308 b in return. One or moresteps of this process may be repeated. Afterwards, BRP 305 may beperformed.

SLS 304 training may use a beacon frame or a SSW frame. When the beaconframe is utilized, the AP/PCP may repeat the beacon frame with multiplebeams/sectors within each BI, and/or multiple STAs may perform BFtraining (e.g., simultaneously). The AP/PCP may not be able to sweep allthe sectors/beams within one BI (e.g., due to the size of the beaconframe). A STA may wait one or more Bls to complete an ISS training.Latency may also be a consideration. When a SSW frame is utilized (e.g.,for point to point BF training), an SSW frame may be transmitted (e.g.,using control PHY) using the SSW frame format shown in FIG. 4 .

FIG. 4 is a diagram of an example frame format for a selection SSWframe. Octets 410 are labeled on the horizontal axis. The format mayinclude Frame Control 401 at octet 2, Duration 402 at octet 2, ReceiverAddress (RA) 403 at octet 6, 404 Transmitter Address (TA) at octet 6,SSW 405 at octet 3, SSW Feedback 406 at octet 3, and Frame CheckSequence (FCS) 407 at octet 4.

FIG. 5 is diagram of an example format for an SSW field in an SSW frame.Bits 510 are labeled in number of bits per element underneath on thehorizontal axis and the bit identifier(s) is correspondingly labeledabove on the horizontal axis. The elements may include Direction 501comprising of 1 bit, Count Down (CDOWN) 502 comprising of 9 bits, SectorID 503 comprising of 6 bits, Directional Multi-Gigabit (DMG) Antenna ID504 comprising of 2 bits, and Receive Sector Sweep (RXSS) 505 lengthcomprising of 6 bits. For example, Sector ID 503 is 6 bits in length andmay occupy bit location B10 through B15.

FIG. 6A is diagram of an example format for an ISS field in an SSWframe. Bits 610 are labeled in number of bits per element underneath onthe bottom of the horizontal axis and the bit identifier(s) iscorrespondingly labeled above on the horizontal axis. The elements mayinclude Total Sectors 601 in ISS comprising of 9 bits, Number of RX-DMGantennas 602 comprising of 2 bits, a Reserved field 603 comprising of 5bits, Poll Required 604 comprising of 1 bit, and another Reserved field605 comprising of 7 bits.

FIG. 6B is a diagram of an example format of an RXSS field in an SSWframe. Bits 630 are labeled in number of bits per element underneath onthe horizontal axis and the bit identifier(s) is correspondingly labeledabove on the horizontal axis. The elements may include Sector Select 621comprising 6 bits, DMG Antenna Select 622 comprising of 2 bits, Signalto Nose Ratio (SNR) report 623 comprising of 8 bits, Poll Required 624comprising of 1 bit, and a Reserved field 625 comprising of 7 bits.

FIG. 7 is a diagram of an example of a Protocol Data Unit (PPDU) 710that may be used for a Physical Layer Convergence Procedure (PLCP). ThePDDU 710 may have several frames/fields, such as a Packet Type TrainingLength (PTTL) fields 701 of training length (N), a beam refinementprotocol (BRP) frame 702, an Automatic Gain Control (AGC) field 703 oftraining length (4N), and BRP training fields 704 of training length(5N). The AGC 703 may be considered to be a part training fields. Thevalue (N) may be the training length (e.g., training length that may begiven in the header filed). The training length may indicate that theAGC 703 is 4N (i.e., 4 times N training lengths) subfields and mayindicate that the TRN-RX/TX field is 5N subfields. In oneimplementation, the PTTL 701 may be a PLCP header 711, the BRP 702 maybe a Medium Access Control (MAC) body 712, the AGC 703 may comprise fourfields 713 a-d, and the BRP training fields 704 may be a series oftraining (TRN) fields 714. Each AGC field 703 may be transmitted by aSingle Carrier (SC) Orthogonal Frequency Division Multiplexing (OFDM)waveform and may be comprised of multiple Golay complementary sequencesof length 64 Ga64 723 a-c, each with a corresponding control 730sequences of Gb64 733 a-e. Also, the TRN-RX/TX 714 may be carried by anumber of SC-OFDM waveform comprised of subfields 7241 a-k. For example,the CE 724 a subfield may be the same as or similar to the one in apreamble and may repeat for five training lengths (5N), where 724 awould be the first and 724 g would be the fifth. Subfields (e.g., allsubfields) in the training fields of PPDU b 710 may be transmitted usingrotated Tr/2-BPSK modulation. Each subfield of the TRN-RX/TX 714, suchas R/T2 724 c, may be comprised of control Golay complementary sequencesof length 128 alternating between Ga128 and Gb128 734 a-e.

As discussed herein, BRP may be a process where a STA improves itsantenna configuration (or antenna weight vectors), such as fortransmission and/or reception. In such a process, BRP training packetsmay be used to train the receiver and/or transmitter antenna. There aretwo types of BRP packets: BRP-RX, such as TRN-RX 714 (e.g., beamformingrefinement protocol receiver) packets, and BRP-TX, such as TRN-TX 714(e.g. beamforming refinement protocol transmitter) packets. A BRP packetmay be carried by a DMG PPDU and may be followed by an AGC field. TheAGC field may be followed by a TX or RX TRN field, for example, as shownin FIG. 7 .

A BRP 702 MAC body 712 frame may be an Action No. ACK frame and may haveone or more of the following fields: Category, Unprotected DMG Action,Dialog Token, BRP Request field, DMG Beam Refinement element, ChannelMeasurement Feedback element 1 to Channel Measurement Feedback elementk.

The 802.11ay physical layer (PHY) and the IEEE 802.11ay MAC layer andmay have at least one mode of operation capable of supporting a maximumthroughput of at least 20 gigabits per second, measured at the MAC dataservice access point, and may maintain or improve the power efficiency(e.g., per station). The 802.11ay PHY and the MAC layer may havelicense-exempt bands above 45 GHz that may have backward compatibilityand/or may coexist with DMG STAs (e.g., legacy) operating in the sameband. 802.11ay may operate in the same band as legacy standards. Theremay be backward compatibility and/or coexistence with legacies in thesame band. 802.11ay may support one or more of the following: multipleinput, multiple output (MIMO) transmission (e.g., single-user (SU)-MIMOand/or multi-user (MU)-MIMO) and/or multi-channel transmission includingchannel bonding and/or channel aggregation.

In one embodiment, the TRN-RX/TX field may be appended to a DMG beaconframe, and Enhanced DMG (EDMG) STAs may be allowed to perform RX/TXtraining using beacon frames. This may be implemented in an enhanced SLSprocess.

FIG. 8 is a diagram of an example enhanced SLS implementation. For agiven beacon interval 800, there may be a beacon transmission interval(BTI) 801, association beamforming training (A-BFT) 802, and/or datatransmission interval (DTI) 803 just as in FIG. 2 . Enhanced SLS,however, may have Beamforming Training Allocation (BTA) 803 a may beused in DTI 803. BTA 803 a may be scheduled using EDMG extended scheduleelement.

As discussed herein, during the initial BTI 801 an initiator AP 801 mayhave a number of sector training beams 811 a-811 d, each with a uniquedirection, such as that indicated by the tear drop beneath each sectortraining beam 811 a-811 d in FIG. 8 . The portions shown in 860 and 861are discussed in further detail with regard to FIG. 10 and FIG. 11 .

In an allocation, an Initiator AP/PCP 810 may repeat the sector sweep inthe same order as in the BTI 801 (e.g., in the Rx mode) for the BTA 803a. Responder EDMG STAs X 820, Y 830, Z 840, and/or STA DMG L 850 mayreceive in a sector which corresponds to a specific sector (e.g., bestsector) during BTI 801 transmit sector sweep (TXSS), such as 821, 831,841, and/or 851, respectively. A sector ACK frame, not shown, may betransmitted from the AP/PCP 810. Through this enhanced SLS, directionalallocation may be introduced to the DTI, and the AP/PCP's receive sectormay be specified and/or used to listen during the allocation.

The transmit sectors/beams may have been trained during a BTI 801 TXSS.A responder STA 820, 830, and 840 may receive sectors/beams that havebeen trained using a TRN-RX field. The TRN-RX field may be appended tothe beacon frame during the BTI 801 TXSS. One or more of the followingaspects may remain in a responding sub-phase of BTA 803 a: a collisionmay happen in the BTA 803 a, and/or collision resolution may be used; amodified responding approach that incorporates a possibility of multiplechannels for feedback may be used (e.g., with multi-channeltransmission); and or, STAs that are not associated with the AP/PCP 810may transmit in the BTA 803 a. As a result of the enhanced SLS,pre-association transmission may be performed.

A-BFT 802 the AP/PCP 810 may transmit in a series of transmit sectors812 a, 812 b, and 812 c, interspersed with receive sectors 812 d. Thetransmissions may include omni-directional transmissions, for example asindicated by the semi-circle above 812 a, 812 b, and 812 c. The STAs820, 830, 840, and 850 may response with a R-TXSS 822, 832, 842, and852, respectively.

FIG. 9 shows a diagram focusing on the DTI 803 portion on the right sideof FIG. 8 . FIG. 9 is similar to FIG. 8 in so far as elements aresimilarly numbered. FIG. 9 differs, however, in showing an example of abaseline responding implementation in BTA 803 a. A responding frame,such as 823 a, 833 a, and 843 a, may be transmitted by a responding STA820, 830, and 840, respectively, in an initiator's 810 sector detected(e.g., as the best one) during a previous BTI 801 TXSS.

The PCP/AP 810 may repeat a sector sweep in the same order as the sectorsweep in the BTI 801 (e.g., in the RX mode). The PCP/AP 810 may repeat a(e.g., each) sector one or more times in a Space Time Slot (STS) 863.The STSs of solid lines are meant to demonstrate communication for anassociated STA and STSs of dotted lines are meant to demonstratecommunication for unassociated STAs. In one example, the BTA 803 a mayinclude one or more sub-phases 813 a-813 d. The sub-phases 813 a-813 dmay include a responding sub-phase 823 a, 833 a, and 843 a. In theresponding sub-phases 823 a, 833 a, and 843 a, STAs 820, 833, and 843,respectively, may transmit a response to the AP/PCP 810. For example, insub-phase 813 b the AP 810 may keep its receive beam constant over the 4STSs. STA 820 selects the 2nd STS of sub-phase 813 b and transmits 823 awhile STA 840 selects STS 4 of sub-phase 813 b and transmits 843 a. Insub-phase 813 d the AP 810 keeps its receive beam constant over the 4STSs. STA 830 selects the 3rd STS of 813 d and transmits 833 a.

For each responding sub-phase 823 a, 833 a, and 843 a, there may be anacknowledgement (ACK) sub-phases. For example, the AP 810 may send aSector ACK 873 on each STS and STA 820, 830 and 840 receive the sectorACKs on 823 b, 833 b and 843 b. Alternatively, a sector ACK frame may betransmitted from an AP/PCP in each sector following a sector sweep. Asdiscussed herein, a sector and sub-phase may be used interchangeably.

FIG. 10 is a diagram of an example signal configuration of a DMG beaconframe showing, amongst other elements, the STS length. In oneembodiment, the signal 1000 may begin with a Legacy Short Training Field(L-STF) 1001, followed by a Legacy Channel Estimation Field (L-CEF)1002, followed by a Legacy Header (L-Header) 1003, followed by Data1004, followed by the number of STS 1005, followed by the AGC 1006, andfollowed by TRN-RX 1007. The aforementioned order may be re-arranged asneeded and is only an example of one configuration. The number of STSs1005 for a sector may be equal or unequal. The number of STSs 1005 for asector may be fixed or negotiable. An STS configuration (e.g., whetherthe STS configuration for a sector is unequal and/or negotiable) may betransmitted in an EDMG beacon frame corresponding to a sector.

FIG. 11 shows a diagram focusing on elements 860 and 861 from the leftportion of FIG. 8 . FIG. 11 is similar to FIG. 8 in so far as elementsare similarly numbered. FIG. 11 differs, however, in showing the detailof elements 860 and 861. Initiator EDMG AP 810 may undergo BTI with DMGbeacon sectors of 811 a, 811 b, 811 c, and 811 d. Circle 860 highlightswhere a DMG beacon sector 821 was received at a responder EDMG STA x 820from initiator DMG beacon 811 b. The DMG beacon interval 811 b with asector ID=1 may have an example signal configuration 1000 shown in thedotted circle 860. The signal configuration 1000 of the DMG beacon isthe same as the signal configuration discussed in general terms relatedto FIG. 10 . The number of STSs in the signal configuration 1000 may beassociated with the ID, which is equal to 1 based on the sector ID=1shown in DMG beacon 811 b. Also in the example shown in 861, the TRN-RX1007 may be further comprised of one or more TRN-R including Golaycomplementary sequences 1007 a-d and may be preceded by an Omni-RX 1008.

FIG. 12 shows a diagram of an example situation where during BTA 803 athere may be collisions in the responses for directional reception at aninitiator. FIG. 12 is similar to FIG. 8 in so far as elements aresimilarly numbered. FIG. 12 differs, however, in showing a collisionscenario. The dotted blocks shown in white, such as 1201 a-1201 h,represent associated STA responses 1201 sent to the initiator EDMG AP810. The blocks shown in black, such as 1202 a-202 f, representunassociated STA responses 1202. In one or more embodiments, the numberof STSs may differ from sector to sector (e.g., unequal) and/or may benegotiable. The number of STSs for a sector may need to be changed oradapted, such as when there is a collision during an STA responseinterval. For example, 1241 response from responder EDMG STA z 840 maycollide with response 1221 from responder EDMG STA x 820. FIG. 12illustrates an example of varying the number of STS in a beam in an APdirectional Rx interval.

In one or more embodiments, the number of STSs for a given increment(e.g., for a sector) may be equal and/or set by the specification. Inone or more embodiments, the number of STSs for (e.g., each) sector(s)may be equal and/or negotiable (e.g., between a PCP/AP and STAs). ThePCP/AP may modify the number of STSs (e.g., for a sector), for example,based on the presence or absence of collisions (like the example of FIG.12 ). The PCP/AP may modify the number of STS to ensure that a minimumnumber of STSs are used and/or avoid unnecessary overhead. The number ofSTS for a beam may be signaled in the beacon in a field (e.g., a numberSTS field).

FIG. 13 is several examples of a signal configuration based on theunderlying design of the example shown in FIG. 10 , where the number ofSTS varies in size. FIG. 13 is similar to FIG. 10 in so far as elementsare similarly numbered. FIG. 13 differs, however, in showing informationfor x beams (e.g., only for x beams) may be signaled within the STSfield(s). In one or more embodiments, a current beam index and/or a listof beam indices for STSs (e.g., previous STSs) with a correspondingnumber of STSs, may be signaled in a (e.g., each) beacon. For example,in Beacon 0 1010, there may be an initial STS number field for thesession ID 0 1015 a followed by the number of STS (NSTS) 0 1015 b.Similarly, for Beacon 1, there may be a session ID 1 field 1025 afollowed by corresponding NSTS 1 field 1025 b, and a session ID 0 field1025 c followed by a NSTS 0 field 1025 d. As can be seen, this follows apattern, where for Beacon x 1030, where x is any number, there may be anID x field 1035 a followed by an NSTS x field 1035 b, and then an ID x−1field 1035 c followed by an NSTS x−1 field 1035 d, continuing asnecessary until zero fields are reached. Using this system, a receivingSTA may be able to estimate when the STSs may compete as scheduled in agiven beacon.

Table 1 and Table 2 show an example of signaling parameters. Forinstance, looking at Table 1, a slot group with slot ID 2 may start 9slots after the start of the interval and/or may be valid for 4 slots.The entire table, a part of the table, and/or the some or all rows ofthe table (e.g., before a desired beam) may be signaled. The size of thebeacon frame may change from beam to beam. For Table 1 and/or Table 2,it may be assumed that beam x and/or information for the x−1 STSs may besignaled in an N-beam enhanced SLS. A slot group ID of the slot (e.g.,current slot) may be signaled (e.g., first), for example, to simplifydecoding. The decoder may be enabled to (e.g., implicitly) estimate astart of the AGC field.

TABLE 1 Example Signaling with Slot ID and number of STSs Slot ID NSTSslot 0 3 1 6 2 4 3 2 4 1

FIG. 14 is a signal diagram showing an example where a beacon is a fixedsize. FIG. 14 is similar to FIG. 10 in so far as elements are similarlynumbered. FIG. 14 differs, however, in showing one embodiment concerningsignaling design, where the size of the beacon frame may be keptconstant (e.g., by signaling information for some or all N beams).Information for some or all N beam(s) may be signaled. The size of thebeacon frame may be kept constant by signaling information to allow theSTA to estimate (e.g., implicitly estimate) the start of the STSscorresponding to the sector associated with the beacon frame. In theexample shown in FIG. 14 , the STS fields may start with an ID 0 field1405 a followed by an NSTS 0 field 1405 c, and these sets of an ID fieldand an NSTS field may repeat as indicated by fields 1405 c and 1405 d,respectively, until an N−1 repetition is reached indicated by 1405 e and1405 f. The STS fields may eventually culminate in an NSTS N field and aBeacon ID N field, where N is the number of the specific beacon.

Table 2 presents example parameters for the embodiment where the size ofthe beacon frame may be kept constant as well as an STS start index. Arow entry (e.g., a single row entry) of Table 2 may be signaled. The STSstart index for a beam (e.g., a specific beam) and/or the number of STSsavailable for the beam may be signaled in a (e.g., each) beacon.Signaling the STS start index for a beam (e.g., a specific beam) and/orthe number of STSs available for the beam may enable the STA to estimatewhen the STSs for which the STA desires to compete are scheduled.

TABLE 2 Example Signaling with Slot ID, number of STS, and STS startindex STS Start Slot ID NSTS slot Index 0 3 0 1 6 3 2 4 9 3 2 13 4 1 15

FIG. 15 shows a signaling diagram of an example configuration with fixedbeacon size indicating the number of slots to wait before access withthe NSTS slots start index. The fields for the beacon 1500 may besimilar to that of FIG. 10 using like numbers to indicate similarfields, but may differ in the STS fields. Specifically, FIG. 15 includesan ID x 1505 a field, an NSTS x field, and the NSTS slots start indexfield 1505 c, where x is the specific beacon.

In one embodiment, when a STA accesses an STS, there may not be time forchannel assessment (e.g., clear channel assessment) before transmission.Therefore, there may be a need for a transmission protocol for the STAthat differs from legacy CSMA/CA in 802.11. Specifically, when a STAaccesses an STS it may use a modified random access procedure based onan indication of the number of STS resources available.

In one implementation, the modified random access procedure may beginwith the PCP/AP indicating the number of STS resources available and/oran estimate of the number of STAs that may be transmitting (CW). An(e.g., each) STA may generate a number (e.g., a random number) between 1and CW (or 0 and CW−1). If the generated number is less than or equal tothe number of STS resources available (N_(res)), the STA may access theresources (e.g., specific resource). If the generated number is lessthan the number of STS resources available, the STA may randomly accessthe resources (e.g., any of the resources). If the number is greaterthan the number of STS resources available, the STA may subtract thenumber of STA resources from the generated number. The STA may wait forthe next PCP/AP directional RX and/or access the resources (e.g.,specific resource) or a random resource. The STA may send a signal tothe PCP/AP to indicate that the STA is waiting.

In another implementation, an (e.g., each) STA may generate a randomnumber between N_(res) and CW, then follow the remaining steps asdescribed with the random access procedure above.

In another implementation, an STA may perform a modified random accessprocedure and decide to access an STS(s) based on a hash function orsome other function. The STS number N for sector number M for a STA,denoted by N(M)), may be a function or a hash function of one or more ofthe following parameters: association identifier (AID), MAC address orother IDs of the STA (e.g., depending whether a STA has associated withthe PCP/AP or not), timing synchronization function (TSF) timer, thesector number M, the number of space time slots available(N_(available)), and/or the number of space time slots available forsector M (N_(available)(M)). For example, N(M)=f(AIDs, MAC Address, TSFtimer, M, N_(available), N_(available)(M)) or N(M)=hash(AID, MACaddress, TSF timer, M, N_(available), N_(available)(M)).

If one or more channels are available for transmitting BTA, an STA maychoose the STS(s) in one or more of the channels available. For example,the STA may decide to use the STS(s) in a (e.g., the STA's mostpreferred) channel. The channel number on which the STA providesfeedback may be a function of one or more the following parameters: AID,MAC address or other IDs of the STA (e.g., depending whether a STA hasassociated with the PCP/AP or not), TSF timer, and the sector number M,the number of STSs available N_(available), the number of STSs availablefor sector M N_(available)(M), number of available channelsNum_(Channel_available), number of channels available for sector M,and/or Num_(Channel_avalable)(M).

In one embodiment, a signal transmitted may not be STA specific. Forexample, a signal may be energy detected. The signal may inform thePCP/AP that a STA did not receive an acknowledgement of the STA'stransmission.

FIG. 16 is a diagram of an example collision detection process. In oneembodiment, an AP may identify collisions within an AP directionalreceive interval. For example, the AP may identify collisions directlywithin the AP directional receive interval by performing energydetection on an (e.g., each) STS 1601 before decoding the STS. If theSTS energy is below a threshold 1602, an STA may not access the STS andthe AP may use the number of empty STSs identified to adapt/reduce thenumber of STSs for a beam 1603. As the number of empty STSs increases,the number of STSs scheduled for the beam (e.g., that specific beam) maybe reduced. In one example, the NSTS may be reduced if the number ofempty STSs is greater than NSTS_reduce_threshold. If the STS energy isabove a threshold 1604 and/or the STS contains decodable information1605, the AP may identify the STA and/or may send an ACK during thesector ACK interval to the STA 1606. If the STS energy is above athreshold, and/or the STS does not contain decodable information 1607,the AP may identify a collision and the AP may send a collision detectedflag or indicator during the sector ACK interval 1608. The collisiondetected flag or indicator may enable STAs that sent information to theAP and/or did not get an ACK back to confirm that there may have been acollision. The STAs may request additional channel access and/or retryobtaining feedback. The AP may use the collision identified toadapt/increase the number of STSs for a beam 1609. In one example, theNSTS may be increased if the number of STSs with collisions is greaterthan NSTS_increase_threshold. The energy threshold defined for collisionidentification may be fixed by specification or adapted by thespecification, for example, to estimate the number of STAs that wereinvolved in a collision. For example, the AP may direct a STA to send aframe at a desired received signal strength indicator (RSSI) to a set ofpower controlled STAs. The received energy (or RSSI) may be used toestimate the number of STAs involved in the collision. This process mayrepeat 1610 as necessary, and/or for each selected STS that may undergoenergy detection.

FIG. 17 is a diagram showing an example of collision interval for acollision identification scenario. FIG. 17 is similar to FIG. 8 in sofar as elements are similarly numbered. FIG. 17 differs, however, inshowing a Sector ACK Interval 1701, wherein a number of ACK in STS 1711,1712, and 1713 are sent by the initiator EDMG AP 810. The ACK interval1701 may inform STAs 820, 830, and 840 whether the AP 810 receivedtransmissions. In one example, an (e.g., each) STA, such as STA 830,that does not receive sector ACK may transmit a signal 1731 to the AP,for example, when the STA's desired sector is receiving.

Also in FIG. 17 , there may be a collision identifier interval 1702 thatmay be sent after the sector ACK interval 1701, for example, to identifyif there are collisions during the AP 810 directional reception. TheAP/PCP 810 may repeat the sector sweep in the same order as in the BTIand/or in the RX mode, for example, in the collision identificationinterval (e.g., an updated collision identification interval). Forexample, in STS 1703 the AP 810 detects a collision based on energydetect from the signals 1721 and 1741 sent by STAs 820 and 840,respectively.

In one or more embodiments, a STA-specific orthogonal, pseudo-random orsemi-orthogonal sequence may be appended to the end of the STA responseframe (e.g., the short sector sweep frame). As an example, in an OFDMwaveform scenario, an (e.g., each) STA may be assigned sub-carriers(e.g., specific sub-carriers) to transmit on. The AP may identify STAsthat transmitted by identifying subcarriers/sub-carrier groups (e.g.,with energy on the subcarriers/sub-carrier groups). The AP may beallowed to identify (e.g., separately identify) STAs if a collisionoccurs.

FIG. 18 is a diagram of an example implementing a STA specificidentifier for STA specific collision identification. A signaltransmitted may be specific to a STA and/or enable identification of theSTA based on an orthogonal or semi-orthogonal code. FIG. 18 may besimilar to FIG. 8 in so far as elements are similarly numbered. FIG. 18differs, for example, in showing an AP directional RX where collisionsare occurring 1800. In a given interval/frame, there may be a number ofSTS 1811, 1812, 1813, 1814, 1815, and 1816. A collision may be detectedat STS 1812 as a result of a signal sent by STA 820 and STA 830 becauseeach signal may have a feedback portion 1860 and a separable identifier1861 which may enable the AP 810 to identify which signal belongs toeach STA. For example, the STA 820 signal 1821 may comprise a SSW 1822and a STA specific separable identifier 1823. Similarly, the STA 830signal 1831 may comprise a SSW 1832 and a STA specific identifier 1834.

FIGS. 19, 18, and 20 are signal configurations relating to collisionrecovery. In one or more embodiments, a PCP/AP may schedule additionalslots for the sector that PCP/AP identifies as having collisions for a(e.g., the next) beamforming training allocation period by incrementingthe number of STS in the AP directional reception interval. In oneinstance, a PCP may create a beam collision recovery interval (e.g.,immediately after the sector ACK). In another instance, an AP may sendadditional feedback scheduling information within the sector ACKinterval for specific sectors (e.g., only collision sectors) concerningcollision identification within a AP directional receive interval.

FIG. 19 is a signal configuration example for a sector ACK frame withequal collision recovery STSs. In the example shown in FIG. 19 , theremay be a sector ACK header 1901 followed by the STA acknowledgement foreach STA, such as STA 1 ACK 1902 all the way 1903 to an Nth STA ACK1904. When beam collision is enabled, there may be a field 1905 toindicate that a collision is present.

In a scenario where the AP is not able to identify the STAs (e.g., thespecific STAs), the AP may signal if there has been a collision or not.The AP may signal information to enable a beam recovery interval (e.g.,immediately after the sector ACK) and/or to enable the STAs to retryobtaining feedback. The AP may also signal additional STS opportunitiesfor the collision sectors. In order to do this, there may be a field toidentify the sectors that the AP has identified as having had collisions(e.g., the collision sectors). For example, the number of STS 1907 for abeam may be equal to reduce signaling complexity, in which case thenumber of previous beams 1906 and the number of STS 1907 is included inthe signal.

FIG. 20 illustrates an example of sector ACK frame with collision beamspecific recovery STS. In one or more embodiments, the number of STSsfor a collision sector may be collision sector specific. FIG. 20 may besimilar to FIG. 19 in that elements 1901-1904 are the same as elements2001-2004. FIG. 20 differs from FIG. 19 , however, because it representsa scenario where the number of STS per collision sector may be collisionsector specific. The AP may signal information that a collision ispresent 2005 to enable a beam recovery interval (e.g., immediately afterthe sector ACKs) and/or to enable the STA to retry obtaining thefeedback. The AP may send the STS start index 2006 and number of STSs2007 which indicate that the AP may go into another set of STSs withspecific beams on a specific STS so that the STA knows when to try againto recover from the collisions.

FIG. 21 is a signal configuration of an example sector ACK frame withcollision identification and STA specific beam collision/recoverysignaling. FIG. 21 may be similar to FIG. 19 in that elements 1901-1904are the same as elements 2101-2104. FIG. 21 differs from FIG. 19 ,however, because it represents a scenario where the AP is able toidentify a STA with the collision (e.g., specific STAs), and the AP maysignal if there has been a collision or not and/or signal information tothe STA informing the STA that there has been a collision. For example,in FIG. 21 STA 1 a collision is indicated in 2106, and this is repeated2107 as necessary, until the nth STA that collided 2108 has beenreported. The AP may poll an STA (e.g., each STA individually) or sendinformation to an STA (e.g., each) indicating the STS the STA may use tosend information during the recovery.

In one or more embodiments, the PCP/AP may schedule additional feedbackduring a directional allocation region, for example, on identifyingcollisions within a beam. The directional allocation region may includea region in the DTI. In the DTI, the PCP/AP may specify the AP's receivesector that the PCP/AP may use to listen during the allocation. In theinterval, one or more of dedicated feedback using SPs (and e.g., STAspecific STSs SPs) and/or contention based feedback using CBAPs (ore.g., scheduled STSs) may be used. Additionally, the PCP/AP may scheduleadditional slots for the sector it identifies as having collisionsduring the next BTA period by incrementing the number of STS in the APdirectional reception interval.

From an STA perspective, this means that an STA may consider thefeedback received from the AP/PCP so that it may respond in theadditional STS in the next BTA period, where the feedback may occurbased on anyone of the embodiments, or combination of embodiments, asdiscussed herein. For example, if an ACK is not received by a STA, andthe AP provides additional STS due to collisions, then the STA may tryagain in the next BTA for the sector the PCP/AP identified as havingcollisions.

In one or more embodiments, unassociated STAs may need a procedure forbeing addressed by an AP during an enhanced SLS situation. Anunassociated STA may respond to the SLS in the AP directional receptionregion. Unassociated STAs may not have an AID in the SSW frame to enablethe AP to identify the unassociated STAs. To identify the unassociatedSTAs, the STAs may respond using one or more procedures.

In one example, the STAs may respond using a fixed Association ID (AID).The fixed AID may inform the AP to initiate association within thereception sector.

In another example, the STAs may respond using a fixed AID with a randomnumber generated to identify the STA (e.g., the specific STA). The fixedAID with a random number generated may enable the AP and/or the STA toidentify each other. The fixed AID with a random number generated mayinform the AP that the AP may commence an association implementation forthe STA (e.g., the specific STA). The STAs may respond using randomselection of an AID (e.g., from a preselected set of AIDs).

In another example, random selection of an AID may enable the AP and/orSTA to identify each other. Random selection of an AID may inform the APthat the AP may commence the association implementation for the STA(e.g., the specific STA).

FIG. 22 is a diagram showing one or more of the embodiments describedherein concerning an enhanced SLS procedure(s). Like numbering fromother figures may be considered to be the same or similar elements. Inone or more embodiments, the unassociated STAs may use an STS (e.g., anyof the STS available). Alternatively, the unassociated STAs may use areserved set of STSs, such as those shaded STS 1202. In one example, theunassociated STAs may access a set of STSs, such as those STS with solidlines (e.g., with lower priority) to minimize collision with theassociated STAs.

As discussed with regard to FIGS. 19, 20, and 21 , for a Beam RecoveryInterval 2201, the AP/PCP 810 may send feedback 2211 and 2212 after acollision, so that STAs, such as 821 as 841, may retry transmission 2221and 2243, respectively.

Although the features and elements of the present invention aredescribed in the preferred embodiments in particular combinations, eachfeature or element may be used alone without the other features andelements of the preferred embodiments or in various combinations with orwithout other features and elements of the present invention. Althoughthe solutions described herein consider 802.11 specific protocols, it isunderstood that the solutions described herein are not restricted tothis scenario and are applicable to other wireless systems as well.Throughout the solutions and provided examples, the blank areas in thefigures may imply that there is no restriction for this area and anysolution can be employed.

The processes described above may be implemented in a computer program,software, and/or firmware incorporated in a computer-readable medium forexecution by a computer and/or processor. Examples of computer-readablemedia include, but are not limited to, electronic signals (transmittedover wired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and/or removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, terminal, base station, RNC, and/or any host computer.

What is claimed is:
 1. A method implemented at a responder, the methodcomprising: receiving, from an initiator, an indication of a number ofslots for communicating in a sector of the initiator; sending a signalin one or more slots of the indicated number of slots for communicatingin the sector of the initiator based on a generated random number beingless than the number of slots for communicating in the sector of theinitiator; and receiving an acknowledgement (ACK) confirming the signalwas received by the initiator.
 2. The method of claim 1, wherein the ACKis received in a sector of a sector sweep.
 3. The method of claim 1,wherein the responder is an enhanced directional multi-gigabit (EDMG)station.
 4. The method of claim 1, wherein the signal is sent in adirection based on training that occurred during a beacon transmissioninterval (BTI).
 5. The method of claim 1, wherein the number of slotsfor communicating in the sector of the initiator is an equal or unequalnumber compared to another sector.
 6. The method of claim 1, wherein theslots for communicating in the sector of the initiator are space timeslots (STSs).
 7. The method of claim 1, wherein the initiator that sentthe indication of the number of slots for communicating in the sector isassociated with the responder.
 8. The method of claim 1, wherein theinitiator that sent the indication of the number of slots forcommunicating in the sector is unassociated with the responder.
 9. Themethod of claim 1, wherein a beacon frame comprises the indication ofthe number of slots for communicating in the sector of the initiator,and wherein the method further comprises receiving the beacon frame fromthe initiator.
 10. The method of claim 9, wherein the number of slots isindicated in a field of the beacon frame.
 11. The method of claim 10,wherein the beacon frame is a directional multi-gigabit (DMG) beaconframe.
 12. The method of claim 1, wherein the slots are associated witha beam training allocation.
 13. The method of claim 12, wherein the beamtraining allocation is an asymmetric beamforming training allocation.14. The method of claim 1, wherein sending the signal in the one or moreslots from the indicated number of slots based on the generated randomnumber being less than the number of slots for communicating in thesector of the initiator comprises: generating the random number; andcomparing the generated random number to the indicated number of slots.15. A wireless transmit receive unit (WTRU) configured to operate as aresponder, the WTRU comprising: a transceiver; and a processorconfigured to: receive, from an initiator via the transceiver, anindication of a number of slots for communicating in a sector of theinitiator; send, via the transceiver, a signal in one or more slots ofthe indicated number of slots for communicating in the sector of theinitiator based on a generated random number being less than the numberof slots for communicating in the sector of the initiator; and receivean acknowledgement (ACK) from the initiator.
 16. The WTRU of claim 15,wherein the ACK is received in a sector of a sector sweep.
 17. The WTRUof claim 15, wherein the WTRU is an enhanced directional multi-gigabit(EDMG) station.
 18. The WTRU of claim 15, wherein the signal is sent ina direction based on training that occurred during a beacon transmissioninterval (BTI).
 19. The WTRU of claim 15, wherein the number of slotsfor communicating in the sector of the initiator is an equal or unequalnumber compared to another sector.
 20. The WTRU of claim 15, wherein theslots for communicating in the sector are space time slots (STSs). 21.The WTRU of claim 15, wherein the initiator that sent the indication ofthe number of slots for communicating in the sector is associated withthe WTRU.
 22. The WTRU of claim 15, wherein the initiator that sent theindication of the number of slots for communicating in the sector isunassociated with the WTRU.
 23. The WTRU of claim 15, wherein a beaconframe comprises the indication of the number of slots for communicatingin the sector of the initiator, and wherein the processor is configuredto receive the beacon frame via the transceiver.
 24. The WTRU of claim23, wherein the number of slots is indicated in a field of the beaconframe.
 25. The WTRU of claim 24, wherein the beacon frame is adirectional multi-gigabit (DMG) beacon frame.
 26. The WTRU of claim 15,wherein the slots are associated with a beam training allocation. 27.The WTRU of claim 26, wherein the beam training allocation is anasymmetric beamforming training allocation.
 28. The WTRU of claim 15,wherein the processor being configured to send the signal in one or moreslots from the indicated number of slots based on the generated randomnumber being less than the number of slots for communicating in thesector of the initiator further comprises the processor being configuredto: generate the random number; and compare the generated random numberto the indicated number of slots.